Computer systems/section 1.5 Flashcards
Denary numbers
Base 10, uses digits 0 - 9
Binary numbers
Base 2, uses digits 0 and 1
8-bit binary
8 digits, where 255 is the maximum denary value an 0 is the minimum
The mantissa
The significant figures of the actual digits of the number
e.g. in 0.2345 x 1o^5, 2345 is the mantissa
Exponent
In 10^n, n is the exponent; tells you how many places to move the decimal point in the mantissa
e.g. in 0.2345 x 10^5, 5 is the exponent
Bitmap graphic
A 2D array of pixels
Resolution
(In a bitmap graphic)
The total number of pixels in an image
Bit depth
(In a bitmap graphic)
Defines the number of colours available
e.g. 8-bit is a bit depth, means there are 2^8, or 256, colours
Higher resolutions means…
better quality but greater file size
Lower resolution means…
lower file size but poorer quality
How are bitmap graphics stored?
Each pixel is stored as a binary value
Vector graphics
A list of attributes that are used by the computer to create images
Scaling vector graphics…
does not affect resolution, so quality is unaffected
You can layer vector graphics…
without affecting what is underneath
File size for vector graphics is ____ than bitmap graphics
smaller
unless there are lots of complex shapes
Common file format for vector graphics
SVG
Scalable Vector Graphic
Objects in vector graphics
Rectangle, ellipse, line, polygon
Vector attributes
Co-ordinates, fill colour, line colour
CPU
Central processing unit, handles all instructions that make hardware and software run normally
ALU
Responsible for arithmetic (add, subtract etc.) and logical operations (AND, OR etc.)
Calculating brain of the CPU, processes the data
Arithmetic logic unit
Calculating brain of the CPU
ALU/Arithmetic Logic Unit
CU
Controls the operations of the processor, decodes the program instructions, manages other parts of the CPU to carry out instructions
Control Unit
Registers
Storage locations for data being processed by the CPU, and instructions that are being executed
Storage location for data being processed by the CPU, and instructions that are being executed
Registers
ACC (Accumulator)
Stores intermediate results of calculations
Type of register
Type of register that stores intermediate results of calculations
ACC/Accumulator
Program Counter (PC)
Holds the memory address of the next instruction that should be executed
Type of register
Type of register that holds the memory address of the next instruction that should be executed
Program Counter/PC
Memory Address Register (MAR)
Holds the address of the data being accessed in memory
Type of register
Type of register that holds the address of the data being accessed from memory
Memory Address Register/MAR
Memory Data Register (MDR)
Holds the data that has been fetched from memory
Type of register
Type of register that holds the data that has been fetched from memory
Memory Data Register/MDR
Current Instruction Register (CIR)
Holds the current instruction being executed, splits the operation into what to do and where to do it
Type of register
Type of register that holds the current instruction being executed
Current Instruction Register (CIR)
RAM
When a program is running, the data that will be processed is temporarily stored in the RAM, until the data is needed by the processor
When a program is closed…
RAM
The data held in RAM is deleted
When the computer shuts down…
RAM
RAM completely clears
Buses
Systems of electrical pathways that carry data to and from the other parts of the processor, as well as between the processor and other components
Data bus
Carries the data being processed
Address bus
Carries the addresses of data and instructions, so that data can be sent and recieved to/from the right location
Control bus
Carries the control signals from the Control Unit to manage computer operations
Carries the data being processed
Data bus
Carries the addresses of data and instructions, so that data can be sent and recieved to/from the right location
Address bus
Carries the control signals from the Control Unit to manage computer operations
Control bus
Translators
Translate code created by programmers into binary
Compiler
A type of translator that translates source code into object code, which is stored in a new file (the object code does not need translator software to run)
TRANSLATES ONCE
Interpreter
A type of translator that translates source code directly into machine code, and it runs through the entire translation and execution process
TRANSLATES AS YOU GO ALONG
Types of translators
Interpreters, compilers
Monitor settings to limit environmental impact
- Reduce brightness
- Activate efficiency mode if the monitor supports the setting
- Do not use a screen saver
Power down settings to limit environmental impact
- Power down the monitor when you aren’t using it/after a set period of inactivity
Standby mode
- Where the user isn’t using the computer
- RAM is still powered
- Data for software running is temporarily stored until you turn on the computer
- Power to other computers is reduced or turned off
Hibernate mode
- Contents of RAM are copied to the hard disk
- Hard disk saves a permanent copy
- Turns off almost all components
How is data sent across a network?
It is split into packets
Firewall
Checks data packets as they are sent or received from a system or network
What does a firewall check?
- Check that data packets meet specific rules before being transferred
- Sets rules about what stations on a network can send or receive packets
What do a firewall’s rules account for?
- Sender IP address
- Receiver IP address
- Port numbers
- Protocols
What is the purpose of firewalls?
Protect against unauthorised access to a computer system
Encryption
When data is scrambled during transmission to prevent unauthorised access
What does encryption do?
- Uses algorithms to create keys that can encrypt data
- Keeps the key secure by using public and private keys during transmission of data
